WA What is the Statute of Limitations to Sue for Negligence?

Hi
I am new to this and was hoping to get some help. I have a friend who is currently in
prison and was bashed up in prison and subsequently admitted to a hospital. What is the
statute of limitations of suing for
negligence?

Apparently there is no investigation done after the incident. One of his pal tried asking the officer what actually happened, but no one is giving them any answer.

Also, it must have been really bad for him to be admitted to the hospital. He just wants to know what happened and who attacked him. He is unsure what to do as he doesn't have any savings to hire a lawyer to find out what exactly happened.